The Seventh International Workshop on Immune-Deficient Animals will be held in Bar Harbor, Me, 25-29 September, 1991. This seventh workshop builds on the highly successful workshops held every three years since the original workshop in Aarhus, Denmark in 1973. The last International Workshop on Immune-Deficient Animals was held in Beijing, China in 1988. Emphasis will be placed on the development and use of animal models for immunologic dysfunction, with sessions on development and regulation of the immune system, heritable immunodeficiency disease, acquired immunodeficiency syndrome, infectious diseases, and cancer. The major focus of this workshop will be recent advances in the use of animal models in increasing the understanding of the immune system in normal and pathologic states and to introduce new animal models for immunodeficiency disease. Each session will begin with an invited presentation providing and overview of the research problems and progress in the specific area. These overviews will be followed by two additional invited presentations and four more narrowly focused complementary presentations. Presenters will be selected by the Organizing Committee from attendee applications. Attendance will be limited to 100. Participation of graduate students and postdoctoral students is encouraged. Poster presentations are encouraged. Abstracts will be provided to attendees. Submitted manuscripts will be encouraged and accepted papers will be published. A major focus of this workshop will be to foster interaction among those researchers that develop animal models for immunodeficiency and investigators searching for better research tools with which to probe the immune system.